Our invention relates to the holding during machining operations of workpieces that include surfaces shaped like circular arcs, and more particularly to chucks and methods of clamping or chucking for circular arcuate workpieces that are less than 360 degrees in circumferential extent but that are not equal to 180 degrees.
Simple mechanisms are available for holding workpieces that are circular, and workpieces that have portions that are circular arcs equal to 180 degrees can be placed in an opposed mating relationship that permits them also to be held by simple mechanisms. However, when a workpiece essentially is shaped like a circular arc that is less than 360 degrees but is not equal to 180 degrees, such simple mechanisms can not be employed for accurate and close tolerance machining operations. In particular, when such a workpiece is a concave circular arcuate bearing that must be chucked for machining by rotation at high speed on a lathe, prior art chucks and methods of chucking are deficient.